Systems and Methods for Removing Micro-Particles from a Metalworking Fluid

ABSTRACT

A method of removing metal particles from a contaminated metalworking fluid comprising emulsion droplets and metal particles includes pressurizing a first clean metalworking fluid with gas to provide an aerated metalworking fluid; releasing the pressure of the aerated metalworking fluid to form a plurality of bubbles; applying a shear force to the contaminated metalworking fluid to separate the emulsion droplets from the metal particles; flowing the contaminated metalworking fluid with the aerated metalworking fluid in a laminar flow to form a combined fluid, wherein the flowing occurs during the formation of the plurality of bubbles and while the emulsion droplets are separated from the metal particles, and wherein the laminar flow lasts for a time sufficient for the plurality of bubbles to attach to the metal particles; releasing the combined fluid into a flotation tank; and removing the metal particles to form a second clean metalworking fluid.

BACKGROUND OF THE INVENTION

The present invention generally relates to methods and systems forremoval of metal particle from a metalworking fluid, and in particularto methods and systems for removal of metal micro-particles from ametalworking fluid comprising an anionic and/or nonionic emulsifier.

Metal forming or metal deformation processes create very small metalparticles referred to as micro-fines. These particles are typically from30 micron to sub-micron (below one micron) in size. When themetalworking fluid is an emulsion (in particular, an oil-in-wateremulsion), these sub-micron non-ferrous metal particles cannot beremoved by conventional filtration and separation techniques such aspressure media filtration, vacuum assist media filtration, settlingseparation and centrifugation because these methods will remove theemulsion along with micro-fines associated with the fluid from thedeformation process. Since the non-ferrous sub-micron particles have lowmagnetic permeability, they cannot be removed by magnetic separators.Further complicating some of these deformation processes, such as butnot limited to, extrusion deformation, is the fact that there is verylittle carryout on the deformed part. Therefore, the non-ferrousmetallic micro-fines build up in the emulsion lubricant rendering thelubricant saturated with micro-fines after only a few weeks of use. Themicro-fine particles contribute to abrasive wear on the die surfacesresulting in poor surface finish on the deformed part and in some casesthe emulsion may phase separate. One remedy is to perform a partialrelease of the emulsion lubricant, thus diluting the metallic particleloading as expressed in milligrams per liter (mg/L), or a completerecharge of the emulsion lubricant, commonly referred to as a DCR, dumpclean and recharge. A DCR is a waste of product and a potential stresson the environment.

The use of nominal or absolute rated filter media (under vacuum orpressure) is a common practice but filter media rated below 5 micronscan strip out emulsion droplets. Therefore, the filter media cannot beeffective in removing submicron particles. Also, there is a desire tohave “zero-waste” to landfill. Filter media of any kind saturated withmetallic fines and oil is a stress factor on the environment.

To further complicate the particle separation, these micro-fineparticles carry a positive charge when they are immediately strippedaway from the base metal. For example, metallic copper parts have aneffective zero valence expressed as Cu°. However, when these micro-fineparticles are stripped away from the base part, they are driven to afree ion form and carry two positive charges and expressed as Cu⁺⁺.Similarly, when aluminum is stripped from its base part in a deformationprocess as referenced above, the result is aluminum converting from Al°to Al⁺⁺⁺. These metals in their ionic form will readily react with anyanion in solution and form an electro-kinetic bond. [See FIG. 1 ]. Thehigher the anionic charge, the more micro-fine particles will adhere tothat anion. In some chemical anionic based emulsions using an oleic acidbased emulsion system, the Cu⁺⁺ or Al⁺⁺⁺ bond form a precipitate or morechemically accurate a metallic soap. The copper and aluminum soaps carrythe micro particles and lubricant to the die surfaces as well as theentire metalworking machine surface. The metallic soap residues willinterfere with the machine functions as well as accelerate die wear aspreviously mentioned.

Conventional methods to weaken or destroy this metallic/anion bonds areto use chelating chemicals such as a sodium salt ofethylenediaminetetraacetic acid (EDTA) or nitrilotriacetic acid (NTA).The use of chelating chemicals are not desired since they bind the metalphase in a chemical complex and make metal separation from the chelatein subsequent wastewater treatment processes very challenging.

There is a need for a method and system for removing micro-fineparticles from a metalworking fluid.

BRIEF SUMMARY OF THE INVENTION

In one embodiment there is a method of removing metal particles from acontaminated metalworking fluid comprising emulsion droplets and metalparticles, the method including pressurizing a first clean metalworkingfluid with gas to provide an aerated metalworking fluid; releasing thepressure of the aerated metalworking fluid to form a plurality ofbubbles; applying a shear force to the contaminated metalworking fluidto separate the emulsion droplets from the metal particles; flowing thecontaminated metalworking fluid with the aerated metalworking fluid in alaminar flow to form a combined fluid, wherein the flowing occurs duringthe formation of the plurality of bubbles and while the emulsiondroplets are separated from the metal particles, and wherein the laminarflow lasts for a time sufficient for the plurality of bubbles to attachto the metal particles; releasing the combined fluid into a flotationtank; and removing the metal particles to form a second cleanmetalworking fluid.

In some embodiments the contacting occurs within about 0.5 second orless after the releasing of the pressure of the aerated metalworkingfluid. In some embodiments the flowing occurs within about 0.5 second orless after applying the shear force. In some embodiments the shear forceis a hydraulic shear force, for example applying a hydraulic shear forceincluding injecting the aerated metalworking fluid into a flow ofcontaminated metal working fluid in a direction perpendicular to theflow of contaminated metal working fluid. In other embodiments the shearforce is a mechanically generated shear force. The amount of emulsifierin the second clean metalworking fluid may be within about 0.1 v % toabout 15 v % of the amount of emulsifier in the contaminatedmetalworking fluid. The coagulation channel may be substantiallystraight.

In another embodiment there is a method for removing metal particlesfrom a contaminated metalworking fluid comprising emulsion droplets andmetal particles, the method comprising: pressurizing the contaminatedmetalworking fluid with gas in a pressurization vessel to provide anaerated metalworking fluid; flowing the aerated metalworking fluid fromthe bottom of the pressurization vessel to a coagulation channel;applying a shear force to the aerated metalworking fluid to separate theemulsion droplets from the metal particles; reducing the pressure of theaerated metalworking fluid to provide a plurality of bubbles, whereinthe reducing the pressure occurs after applying the shear force andwhile the emulsion droplets are separated from the metal particles;flowing the aerated metalworking fluid in a laminar flow through thecoagulation channel to a floatation tank, wherein the laminar flow lastsfor a time sufficient for the plurality of bubbles to attach to themetal particles; releasing the aerated metalworking fluid into theflotation tank; and removing the metal particles to provide a cleanmetalworking fluid. In some embodiments the reducing the pressure isabout 0.5 second or less after applying the shear force. In someembodiments the reducing the pressure occurs within 0.5 second afterapplying the shear force. The shear force may be a mechanicallygenerated shear force. The amount of emulsifier in the cleanmetalworking fluid may be within about 0.1 v % to about 15 v % of theamount of emulsifier in the contaminated metalworking fluid. Thecoagulation channel may be substantially straight.

In some embodiments the time sufficient for the plurality of bubbles toattach to the metal particles is at least about 1.0 second. In someembodiments the metal particles have an average particle size of about30 micron or less. In some embodiments the first clean metalworkingfluid or clean metalworking fluid is pressurized with gas at about 3.5bar to about 6.2 bar for about two minutes or longer. In someembodiments the aerated metalworking fluid and the contaminatedmetalworking fluid are flowed in a flow ratio in a range of 1:5 (v:v) to1:1 (v:v). In some embodiments the metal particles are non-ferrous, forexample, the metal particles may comprise one or more of copper,aluminum, nickel, lead, titanium, tungsten and molybdenum.

In some embodiments the gas comprises atmospheric air. In someembodiments the gas is selected from nitrogen, oxygen, ozone, andcombinations thereof. The gas bubbles may have a size in a range of fromabout 10 microns to about 50 microns.

In some embodiments the contaminated metalworking fluid comprises anemulsifier. Such emulsifier may be an anionic emulsifier, a nonionicemulsifier, a combination of anionic and nonionic emulsifier, or acationic emulsifier. In some embodiments including a nonionic emulsifierand an anionic emulsifier, the nonionic emulsifier is present at about0.1% wt. to 20% wt of the anionic emulsifier. The contaminatedmetalworking fluid may be an oil-in-water phase emulsion. In someembodiments the emulsifier (or emulsion droplets) may have a size in arange of about 10 microns to 1 micron.

The metalworking process may be a metal forming or metal removalprocess.

In another embodiment there is a system for removing particles from acontaminated metalworking fluid. Such system may include apressurization tank; a mechanical shear device; a coagulation channelhaving a length sufficient to provide a laminar flow of a fluid throughthe coagulation chamber for at least about 1 second; and a flotationtank. The coagulation channel may be substantially straight.

In another embodiment there is a system for removing particles from acontaminated metalworking fluid. Such system may include apressurization tank; a hydraulic shear device; a coagulation channelhaving a length sufficient to provide a laminar flow of a fluid throughthe coagulation chamber for at least about 1 second; and a flotationtank. The coagulation channel may be substantially straight.

In some embodiments the hydraulic shear device includes an inner pipe;an outer pipe surrounding the inner pipe and approximately coaxial withthe inner pipe; a first end cap and a second end cap, each sized to sealan end of the inner pipe; and a rod having a first end and a second endand extending through the inner pipe and the through the first end cap,the second end of the rod being connected to the second end cap. The rodmay be capable of pushing the end cap off of the second end of the innerpipe to release a first fluid flowing through the inner pipe in adirection perpendicular to a flow of a second fluid through the outerpipe. The rod may be capable of pulling the end cap on the second end ofthe inner pipe to seal the flow of fluid out of the inner pipe throughthe second end.

In some embodiments the hydraulic shear device includes a pipe and anozzle for injecting a fluid perpendicular to the direction of the pipe.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofembodiments of the methods and systems for separating metal particlesfrom a metalworking fluid, will be better understood when read inconjunction with the appended drawings of an exemplary embodiment. Itshould be understood, however, that the invention is not limited to theprecise arrangements and instrumentalities shown.

In the drawings:

FIG. 1 is a drawing of a typical emulsified oil-in-water metalworkingfluid comprising a water phase and oil droplets surrounded orsubstantially surrounded by emulsifier molecules;

FIG. 2 is a drawing of a typical contaminated metalworking fluidincluding positively charged metal particles;

FIG. 3 is a drawing of flocculated positively charged metal particlesand negatively charged emulsion droplets;

FIG. 4 is a drawing of slightly negatively charged air bubblesassociated with flocculated metal particle and emulsion droplets;

FIG. 5 is a drawing of emulsion droplets separated from metal particlesafter application of shear force to a contaminated metalworking fluid;

FIG. 6A is a side view of a system for removing particles from acontaminated metalworking fluid in accordance with an exemplaryembodiment of the present invention;

FIG. 6B a side view identical to 6A wherein the system components arenumerically labeled;

FIG. 7A is a side view of a system for removing particles from acontaminated metalworking fluid in accordance with an exemplaryembodiment of the present invention;

FIG. 7B is a side view identical to 7A wherein the system components arenumerically labeled;

FIG. 7C is a cut-away view of the hydraulic shear device of the systemfor removing particles from a contaminated metalworking fluid shown inFIGS. 7A-7B;

FIG. 7D is a cut-away view identical to FIG. 7C wherein the systemcomponents are numerically labeled;

FIG. 8A is a side view of a system for removing particles from acontaminated metalworking fluid in accordance with an exemplaryembodiment of the present invention;

FIG. 8B is a side view identical to 8A wherein the system components arenumerically labeled;

FIG. 9A is a side view of a system for removing particles from acontaminated metalworking fluid in accordance with an exemplaryembodiment of the present invention;

FIG. 9B is a side view identical to FIG. 9A wherein the systemcomponents are numerically labeled;

FIG. 10A is a side view of a system for removing particles from acontaminated metalworking fluid in accordance with an exemplaryembodiment of the present invention;

FIG. 10B is a side view identical to FIG. 10A wherein the systemcomponents are numerically labeled;

FIG. 11A is a side view of a system for removing particles from acontaminated metalworking fluid in accordance with an exemplaryembodiment of the present invention; and

FIG. 11B is a side view identical to FIG. 11A wherein the systemcomponents are numerically labeled.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments are described which provide systems and methods ofremoving metal particles from a metalworking fluid, in particular forremoving metal particles having an average size of about 30 microns orless from a metalworking fluid comprising an emulsion, such as anoil-in-water emulsion comprising an anionic and/or nonionic emulsifier.

The methods and systems of the present invention provide severaladvantages over the prior art. The present invention is capable ofremoving particles (e.g., metal particles) having an size or averagesize of about 30 microns to about 10 microns or even smaller fromsolution. The present invention is capable of removing such particleswithout substantially affecting the emulsion composition, that iswithout removing emulsifier droplets from the metalworking fluid. Thebond (e.g., electro-kinetic bond) of the particle (e.g., metal ion) tothe emulsifier (e.g., anionic chemical) is expected to be stable, butthe gas bubble as it comes out of solution preferentially separates theparticle from the emulsifier without damaging or removing the emulsiondroplet or other fluid components. The inventors have discovered thatpreferential separation can be achieved through application of a shearforce to the emulsion-particle flocculant, contacting the fluidcomprising the separated emulsion droplets and particles with a fluidcomprising a dissolved gas for a time sufficient for gas bubbles to formand attach to the particles, and maintaining the contact of the fluidsin a laminar or quiescent flow to avoid the emulsion droplets displacingthe gas bubbles and recombining with the particles. Prior art teaches agentle application of contaminated metalworking solution; shearing thecontaminated metalworking fluid is opposite of common practice. Theremoval of some portion of metal particles from the metalworking fluidallows for an improved stability of the metalworking fluid emulsion byallowing the emulsifiers to better react as anions and not a metal-anioncomplex, which forms when metal particles contaminate the metalworkingfluid. The addition of a nonionic surfactant along with anionicsurfactants at a ratio of about 0.1% wt. to 20% wt. (nonionic/anionic)as the total weight of the emulsifier package is anticipated to improvethe efficiency of the micro particle separation (also used along withhigh shear force enhancement).

Methods

Various embodiments are described which provide methods of removingmetal particles from a metalworking fluid. For example, the removalprocess typically uses dissolved air flotation (DAF) plus shear forcesfollowed by laminar flow fluid alignment and quiescent flotation toseparate metal particles from the emulsion droplets.

The metalworking fluid may be a fluid used in any metalworking process,such as a metal deformation process. Metal removal deformation includesbut is not limited to one or more of the following operations: machiningdeformation, impact deformation, pressure deformation, and extrusiondeformation. Machining deformation processes include, but are notlimited to: drilling, boring, reaming, tapping, thread rolling, threadchasing, hobbing, milling, turning, sawing, planning, scraping,shearing, shaving, broaching, cutting, grinding, polishing, burnishing,and vibratory deburring. Impact deformation processes include, but arenot limited to: stamping, cold forging, warm forging, and hot forging.Pressure deformation processes include, but are not limited to:hydroforming, sintering, hot rolling, and cold rolling. Extrusiondeformation processes include, but are not limited to: wire and rodforming through a die or series of dies. bar to rod rolling, rod tostrip rolling, rod to wire drawing (intermediate wire), and rod to wiredrawing (fine wire). Such metalworking processes can result in metalparticles contaminating the metalworking fluid.

Methods of the present invention can be used to remove metal particlescontaminating a metalworking fluid after a metalworking process. Suchmetal particles may have an average particle size of about 50 micron orless, about 40 micron or less, about 30 micron or less, about 20 micronor less, or about 10 micron or less. In some embodiments such metalparticles may have an average particle size of about 1 micron to about50 microns, about 1 micron to about 40 microns, about 1 micron to about30 microns, about 1 micron to about 25 microns, about 1 micron to about20 microns, about 1 micron to about 10 microns, about 0.1 micron toabout 10 micron, about 0.1 micron to about 20 micron, about 0.1 micronto about 30 micron.

The metal worked (e.g., deformed) and accordingly, the metal particlecontaminants typically comprise non-ferrous metals or non-ferrousalloys, that is, the predominant alloy is not iron. In some embodimentsthe metal worked (e.g., deformed) and accordingly, the metal particlecontaminants comprise or consist essentially of copper, aluminum,nickel, lead, titanium, tungsten, intermetallics such as molybdenum, ora combination thereof.

In general, such metalworking fluid comprises an emulsifier, forming anemulsion. Typically, the emulsion is an oil-in-water emulsion, althougha water-in-oil emulsion is also contemplated. The emulsion may compriseanionic surfactants, dispersants and/or emulsifiers used individually orin combination. The emulsion may comprise nonionic surfactants,dispersants and/or emulsifiers used individually or in combination. Insome embodiments the emulsion may comprise a combination of anionic andnonionic surfactants, dispersants, and/or emulsifiers used individuallyor in combination. For example, in some embodiments the emulsioncomprises a nonionic emulsifier and an anionic emulsifier, wherein thenonionic emulsifier is present at about 0.1 wt % to about 20 wt %, about0.5 wt % to about 15 wt %, about 1 wt % to about 10 wt %, about 10 wt %to about 20 wt %, or about 0.1 to about 5 wt % of the anionicemulsifier. In still other embodiments the metalworking fluid may bebased on a cationic surfactant, dispersant, and/or emulsifier.

Examples of typical emulsifiers are described in U.S. Pat. No. 6,818,809and U.S. Patent Publication No. 20160326017, each of which is herebyincorporated by reference in its entirety.

Anionic emulsifiers include, but are not limited to, fatty carboxylicacids; and phosphated, mixed blend of C12-C14 and C12-C15 ethoxylatedalcohols. Nonlimiting examples of suitable anionic emulsifiers includesodium dodecylbenzene sulfonate, sodium dodecyl sulphate (SDS), sodiumstearate, N-ethoxy sulfonate, alcohol propoxy sulphate (APS),alpha-olefin sulfonate (AOS), alkyl polyalkoxy alkyl sulfonate, alkylaryl polyalkoxy alkyl sulfonate, branched alkyl benzene sulfonate,docusate sodium, guerbet alkoxy sulphate, sulfonated, ethoxylatedalcohol or alkyl phenol, and alkyl alcohol propoxylated sulphate.

In some embodiments the emulsifier is a nonionic emulsifier. Nonionicemulsifiers include, but are not limited to, fatty alcohol ethoxylates,castor-oil based ethoxylates, fatty acid ethoxylates, ethyleneoxide-propylene oxide (EO-PO) block copolymers (poloxamers),sorbitan(ol) ester ethoxylates, lanolin alcohol ethoxylates, polyolesters, and lanolin alcohols. Nonlimiting examples of nonionicemulsifiers include polyhydric alcohol, nonyl phenol, polyoxyethylenealcohol, alkylphenol ethoxylate, NEODOL™, NEODOL™ ethoxylate 91-8,NEODOL™ 67 propoxylated sulphate (N67-7POS), and SYNPERONIC™ PE/F68.

In some embodiments the metalworking fluid comprises a lubricant.Lubricants may include, but are not limited to, petroleum oil, syntheticoils such as polyalphaolefin (PAO) or phosphate ester, natural esters,synthetic esters, soaps (sodium or potassium), waxes, and boroncompounds. In some embodiments the metalworking fluid comprises one ormore other additives, such as stain inhibitors, corrosion inhibitors,anti-microbial compounds, anti-oxidants, alkanolamines, and phosphate EPadditives.

In some embodiments the metalworking fluid is thermally stable in arange of about 70° F. to about 250° F. In some embodiments themetalworking fluid is preferred to be bio-stable, that is, will notreadily grow bacteria or fungus when maintained at concentrations above4% by volume.

Without being bound by theory, it is believed that application of shearforce immediately before or during formation of air bubbles allows forseparation of micro-fine metal particles from the metalworking fluid andemulsion droplets. Referring to FIG. 1 , a typical emulsifiedoil-in-water metalworking fluid comprises a water phase and oil dropletssurrounded or substantially surrounded by emulsifier molecules. The oilmolecule may have a negative charge and the emulsifier molecule may havean oleophilic end that is positively charged and a hydrophilic end thatis negatively charged. The emulsifier molecules arrange around the oildroplet to provide emulsion droplets having a negatively chargedsurface. The emulsion droplet size may be in the range of about 1 micronto about 25 micron, about 1 micron to about 20 micron, about 1 micron toabout 15 micron, about 1 micron to about 10 micron, or about 1 micron toabout 5 micron. In some embodiments the emulsion droplet is at least 1micron.

Still without being bound by theory, referring to FIG. 2 , it isbelieved that contaminated metalworking fluid may have positivelycharged metal particles that are of near micron and/or sub-micronparticle sizes. Referring to FIG. 3 , it is believed that the positivelycharged metal particles and the negatively charged emulsion droplets mayflocculate, that is join together to form larger particles. Referring toFIG. 4 , it is believed that air bubbles produced have a slightlynegative charge and may associate with the flocculated metal particleand emulsion droplets. Referring to FIG. 5 , it is believed thatapplication of a shear force causes disruption of the flocculated metalparticle and emulsion droplets, and separation of the emulsion dropletsfrom the metal particles. Formation of air bubbles during or immediatelyafter application of the shear force allows for the air bubbles toattach to the positively charged metal particles exclusive of emulsiondroplets. Put another way, the shear forces briefly dislodge the metalions from the emulsion surface (e.g., positively charged metal ions fromthe anionic emulsion surface) and are exchanged, in part, with thedissolved gas (e.g., air) coming out of solution as bubbles (e.g., microbubbles). For example, the slightly negatively charged micro-bubbles maycapture the positive metal micro-particles by electro-kinetic attractionand form together during a laminar flow or a quiescent flow.

In some embodiments, a method of removing metal particles from acontaminated metalworking fluid includes pressurizing a cleanmetalworking fluid with gas to provide an aerated metalworking fluid. Aclean metalworking fluid may refer to a fresh, unused metalworkingfluid, or a metalworking fluid that has been recycled or cleaned ofcontaminants, such as metal particles. The clean metalworking fluid maybe pressurized with gas at a pressure and for a duration sufficient toprovide gas bubbles of about 10 micrometers when the pressure isreleased. The clean metalworking fluid may be pressurized with gas atabout 3 bar to about 7 bar, about 3.5 bar to about 6.5 bar, about 3.5bar to about 6.2 bar, or about 4 bar to about 6 bar for about 2 minutesto about 10 minutes or longer, about 2 minutes to about 5 minutes orlonger, about 2 minutes or longer, about 3 minutes or longer, or about 4minutes or longer. In some embodiments the clean metalworking fluid maybe pressurized with gas at about 3.5 bar to about 6.2 bar for about 2minutes or longer.

The clean metalworking fluid may be pressurized with any suitable gasincluding but not limited to gases comprising nitrogen, oxygen, ozone,or mixtures thereof. In some embodiments the gas may be atmospheric air,such as a mixture of gases including about 75% by weight to about 85% byweight nitrogen and about 15% by weight to about 25% by weight oxygen.

In some embodiments, the method of removing metal particles from acontaminated metalworking fluid further includes releasing the pressureof the aerated metalworking fluid to form a plurality of gas bubbles.Releasing the pressure may comprise reducing the pressure to about 2.5bar to about 0.5 bar, about 1.5 bar to about 0.5 bar, or about 1 bar.Releasing the pressure may comprise allowing the pressure of the aeratedmetalworking fluid to return to atmospheric pressure. In someembodiments the bubbles formed have an average size in a range of fromabout 10 microns to about 50 microns, about 10 microns to about 40microns, about 10 microns to about 30 microns, or about 10 microns toabout 20 microns.

In some embodiments, a method of removing metal particles from acontaminated metalworking fluid may further include applying a shearforce to the contaminated metalworking fluid to separate the emulsiondroplets from the metal particles. In some embodiments the shear forceapplied is a hydraulic shear force. The applying a hydraulic shear forcemay include injecting the aerated metalworking fluid into a flow ofcontaminated metalworking fluid in a direction approximatelyperpendicular to the flow of contaminated metalworking fluid, forexample about 75° to about 105°, about 80° to about 100°, about 85° toabout 95°, or about 90° relative to the flow of the contaminatedmetalworking fluid. In some embodiments the aerated metal working fluidmay be injected from the center of the flow of the contaminatedmetalworking fluid and outward perpendicular into the contaminatedmetalworking fluid, as for example, shown in FIGS. 6A-6B. In otherembodiments the aerated metalworking fluid may be injected from theperiphery of the flow of the contaminated metalworking fluid and inwardtoward the center of the flow of the metalworking fluid, as for example,shown in FIGS. 7A-7D. In such embodiments, the aerated metalworkingfluid may be injected via one or more nozzles, and preferably one ormore pairs of nozzles, wherein each nozzle in a pair of nozzles isoriented opposite and towards each other. In some embodiments a nozzleprovides back pressure between about 50 and about 90 PSIG.

In some embodiments the shear force applied is a mechanically generatedshear force, for example as shown in FIGS. 9A-9B. It is preferable thatthe formation of the gas bubbles occurs at a location immediately afterthe point that the high shear forces are applied to the contaminatedmetalworking fluid so that the metal particles dislodged from theemulsion droplet by the shear forces have an opportunity to combine withthe released gas bubbles rather than back to the surface of emulsiondroplets. In some embodiments hydraulic shear application of the aeratedmetalworking fluid can be used in series with mechanical shearequipment. Hydraulic and mechanical methods of shear generating forcesare described above, but this is not limited to any particular sheargenerating device.

In some embodiments, a method of removing metal particles from acontaminated metalworking fluid may further include flowing thecontaminated metalworking fluid with the aerated metalworking fluid in alaminar flow to form a combined fluid. In some embodiments the flowingoccurs during the formation of the plurality of bubbles and while theemulsion droplets are separated from the metal particles.

In some embodiments the aerated metalworking fluid and the contaminatedmetalworking fluid are flowed in a flow ratio in a range of about 1:5v:v to about 1:1 v:v, for example about 1:3 v:v.

In some embodiments the flowing the contaminated metalworking fluid withthe aerated metalworking fluid occurs within about 1 second, about 0.9second, about 0.8 second, about 0.7 second, about 0.6 second, about 0.5second, about 0.4 second, about 0.3 second, about 0.2 second, about 0.1second or less after the releasing of the pressure of the aeratedmetalworking fluid. In some embodiments the flowing occurs within about1 second, about 0.9 second, about 0.8 second, about 0.7 second, about0.6 second, about 0.5 second, about 0.4 second, about 0.3 second, about0.2 second, about 0.1 second or less after the applying the shear force.In some embodiments the flowing occurs at or about the same time as thereleasing of the pressure of the aerated metalworking fluid. In someembodiments the flowing occurs at or about the same time as the applyinga shear force. In some embodiments the applying a shear force occurs atthe same time as the releasing of the pressure of the aeratedmetalworking fluid.

In some embodiments the laminar flow lasts for a time sufficient for theplurality of bubbles to attach to the metal particles. In someembodiments the laminar flow lasts for about 0.3 second or longer, about0.4 second or longer, about 0.5 second or longer, about 0.6 second orlonger, about 0.7 second or longer, about 0.8 second or longer, about0.9 second or longer, or about 1 second or longer. In some embodimentsthe laminar flow lasts for about 0.5 second to about 10 seconds, about0.5 second to about 8 seconds, about 0.5 second to about 5 seconds,about 1 second to about 5 seconds, about 1 second to about 3 seconds, orabout 0.5 second to about 1.5 second.

In some embodiments the laminar flow is through a coagulation channel.The length of the coagulation channel is preferably long enough to allowfor at least about one second of laminar flow. In preferred embodiments,the coagulation channel is substantially straight to allow for laminarflow with minimal turbulence.

In some embodiments, a method of removing metal particles from acontaminated metalworking fluid may further include releasing thecombined fluid into a flotation tank and removing the metal particles toform a second clean metalworking fluid. For example, removing the metalparticles can be by skimming, scooping, or other methods known bypersons of skill in the art.

In some embodiments the amount of emulsifier in the second cleanmetalworking fluid is within about 0.1% v/v to about 15% v/v, about 0.1%v/v to about 10% v/v, about 0.1% v/v to about 5% v/v, about 0.1% v/v toabout 1% v/v of the amount of emulsifier in the contaminatedmetalworking fluid. In some embodiments the amount of emulsifier in thesecond clean metalworking fluid is about 0.1% v/v to about 15% v/v,about 0.1% v/v to about 10% v/v, about 0.1% v/v to about 5% v/v, about0.1% v/v to about 1% v/v less than the amount of emulsifier in thecontaminated metalworking fluid.

In another embodiment, a method for removing metal particles from acontaminated metalworking fluid includes pressurizing the contaminatedmetalworking fluid with gas in a pressurization vessel to provide anaerated metalworking fluid, for example as shown in FIGS. 11A-11B. Thecontaminated metalworking fluid may be pressurized with gas at apressure and for a duration sufficient to provide gas bubbles of about10 micrometers when the pressure is released. The contaminatedmetalworking fluid may be pressurized with gas at about 3 bar to about 7bar, about 3.5 bar to about 6.5 bar, about 3.5 bar to about 6.2 bar, orabout 4 bar to about 6 bar for about 30 seconds to about 10 minutes orlonger, about 1 minute to about 5 minutes or longer, about 2 minutes toabout 5 minutes or longer, about 1 minute or longer, about 1.5 minutesor longer, about 2 minutes or longer, or about 3 minutes or longer. Insome embodiments the contaminated metalworking fluid may be pressurizedwith gas at about 3.5 bar to about 6.2 bar for about 2 minutes orlonger. Gases that may be use include but are not limited to gasescomprising nitrogen, oxygen, ozone, or mixtures thereof. In someembodiments the gas may be atmospheric air, such as a mixture of gasesincluding about 75% to 85% nitrogen and about 15%-25% oxygen.

In some embodiments, a method of removing metal particles from acontaminated metalworking fluid may further include flowing the aeratedmetalworking fluid from the bottom of the pressurization vessel to acoagulation channel. The bottom of the pressurization vessel refers tothe bottom half, bottom one-third, or bottom one-fourth of thepressurization vessel or to the bottom half, bottom one-third, or bottomone-fourth of the aerated metalworking fluid in the pressurizationvessel.

In some embodiments, a method of removing metal particles from acontaminated metalworking fluid may further include applying a shearforce to the aerated metalworking fluid to separate the emulsiondroplets from the metal particles. For example, the shear force may be amechanically generated shear force.

In some embodiments the method further includes reducing the pressure ofthe aerated metalworking fluid to provide a plurality of bubbles,wherein the reducing the pressure occurs after applying the shear forceand while the emulsion droplets are separated from the metal particles.Releasing the pressure may comprise reducing the pressure to about 2.5bar to about 0.5 bar, about 1.5 bar to about 0.5 bar, or about 1 bar.Releasing the pressure may comprise allowing the pressure of the aeratedmetalworking fluid to return to atmospheric pressure. In someembodiments the reducing the pressure occurs within about 1 second,about 0.9 second, about 0.8 second, about 0.7 second, about 0.6 second,about 0.5 second, about 0.4 second, about 0.3 second, about 0.2 second,about 0.1 second or less after the applying the shear force. In someembodiments the bubbles have an average size in a range of from about 10microns to about 50 microns, about 10 microns to about 40 microns, about10 microns to about 30 microns, or about 10 microns to about 20 microns.

In some embodiments the method further includes flowing the aeratedmetalworking fluid in a laminar flow through the coagulation channel toa flotation tank.

In some embodiments the laminar flow lasts for a time sufficient for theplurality of bubbles to attach to the metal particles. In someembodiments the laminar flow lasts for about 0.3 second or longer, about0.4 second or longer, about 0.5 second or longer, about 0.6 second orlonger, about 0.7 second or longer, about 0.8 second or longer, about0.9 second or longer, or about 1 second or longer. In some embodimentsthe laminar flow lasts for about 0.5 second to about 10 seconds, about0.5 second to about 8 seconds, about 0.5 second to about 5 seconds,about 1 second to about 5 seconds, about 1 second to about 3 seconds, orabout 0.5 second to about 1.5 second.

In some embodiments the length of the coagulation channel is preferablylong enough to allow for at least about one second of laminar flow. Inpreferred embodiments, the coagulation channel is substantially straightto allow for laminar flow with minimal turbulence.

In some embodiments the method further includes releasing the aeratedmetalworking fluid into the flotation tank; and removing the metalparticles to provide a clean metalworking fluid.

In some embodiments the amount of emulsifier in the clean metalworkingfluid is within about 0.1 v % to about 15 v %, about 0.1 v % to about 10v %, about 0.1 v % to about 5 v %, about 0.1 v % to about 1 v % of theamount of emulsifier in the contaminated metalworking fluid. In someembodiments the amount of emulsifier in the clean metalworking fluid isabout 0.1 v % to about 15 v %, about 0.1 v % to about 10 v %, about 0.1v % to about 5 v %, about 0.1 v % to about 1 v % less than the amount ofemulsifier in the contaminated metalworking fluid.

In some embodiments a method for removing metal particulates from ametalworking fluid described above comprises a phase in a multi-phasepurification process. In some embodiments a multi-phase purificationprocess comprises separating large particles, e.g., those greater thanabout 10 microns, by conventional means such as, basic settling,filtration (gravity, vacuum assist, or pressure assist), hydrocyclones,centrifugation.

The embodiments described above for removing microparticles from ametalworking solution can be included as part of a multistagepurification process, for example as shown in FIGS. 8A-8B, 10A-10B, and11A-11B. In some embodiments, a multistage purification method comprisesflowing contaminated metalworking fluid from a metalworking (e.g.,deformation) process into a basic gravity settling tank where the metalparticles readily drop out of the continuous solution because of asignificant difference of specific gravity of the metallic particleversus the metalworking fluid. The solution overflows to a pump liftstation where the contaminated metalworking fluid is injected into aclean (e.g., recycled) fluid and sheared and flowed together, forexample as depicted in FIGS. 6A-6B or FIGS. 7A-7D. The now air and metalparticle complex will rise in the flotation tank, where they will beskimmed off, e.g., by skimming rakes. The cleaned fluid moves downwardthrough the flotation tank and may be directed to the pump circuit forthe recycle pressurization piping loop or may be returned to themetalworking process.

In another embodiment of a multistage purification process, for exampleas shown in FIGS. 10A-10B, contaminated metalworking fluid from thedeformation process enters a basic gravity settling tank where the metalparticles readily drop out of the continuous solution because of asignificant difference of specific gravity of the metallic particleversus the metalworking fluid. The solution overflows to a pump liftstation where a mechanically generated shear is applied to thecontaminated metalworking fluid as depicted in FIGS. 9A-9B. As describedabove, the shear forces dislodge the positively charged metal ions fromthe emulsion surface and are exchanged, in part, with the dissolved gascoming out of solution as micro bubbles. Without being bound by theory,it is believed that the slight negative charge micro bubbles capture thepositive metal micro-particles by electro-kinetic attraction and formtogether within the coagulation channel. The now air and metal particlecomplex will rise in the flotation tank, where they will be skimmed offby the skimming rakes. The cleaned fluid will move downward through theflotation tank. In some embodiments the clean metalworking fluid may bedirected to the pump circuit for the recycle pressurization piping loopor may be returned for use in the metalworking process, as shown inFIGS. 10A-10B. In other embodiments the clean metalworking fluid may bereturned for use in the metalworking process only, or the pressurizationloop may be eliminated, as shown in FIGS. 11A-11B.

Systems

Methods of the present invention are particularly useful in conjunctionwith the systems described herein. Referring to the drawings in detail,wherein like reference numerals indicate like elements throughout, thereis shown in FIG. 6B a system for removing particles from a contaminatedmetalworking fluid, generally designated (100), in accordance with anexemplary embodiment of the present invention. A pressurization tank(not shown) for pressurizing a clean metalworking fluid with a gas is influid connection via conduit (101) with a hydraulic shear device (102).The hydraulic shear device (102) is in fluid connection with a conduit(104) for contaminated metalworking fluid. Conduit (104) is in fluidconnection with coagulation channel (103). The hydraulic shear device(102) releases an aerated, pressurized fluid substantially perpendicularto the flow of the contaminated metalworking fluid into coagulationchannel (103). Hydraulic shear device (102) comprises inner pipe (105)and outer pipe (106). Inner pipe (105) has a first end (112) and asecond end (113). Outer pipe (106) surrounds inner pipe (105) and isapproximately coaxial with inner pipe (105). First end cap (107) issized to seal the first end (112) of the inner pipe (105) and second endcap (108) is sized to seal the second end (113) of the inner pipe (105).Rod (109) has a first end (110) which extends through first end cap(107) and attaches to a pressure adjustment handle (114) and a secondend (111) which attaches to second end cap (108). Rod (109) extendsthrough the inner pipe (105) and is capable of pushing the second endcap (108) off of the second end (113) of the inner pipe (105) to releasea first fluid (e.g., an aerated fluid) flowing through the inner pipe(105) in a direction perpendicular to a flow of a second fluid (e.g., acontaminated metalworking fluid) through the outer pipe (106), therebycreating shear. Rod (109) is also capable of pulling the second end cap(108) on the second end (113) of the inner pipe (105) to seal the flowof fluid out of the inner pipe (105) through the second end (113). Themovement of rod (109) can be controlled by the pressure adjustmenthandle (114).

Still referring to FIG. 6B, the contaminated metalworking fluid and theaerated fluid are contacted through the hydraulic shear and are flowedthrough the coagulation chamber (103). In some embodiments thecoagulation channel may have a length sufficient to provide a laminarflow of a fluid through the coagulation chamber for at least about 1second. Coagulation channel (103) is preferably substantially straight,as shown in FIG. 6B. The coagulation channel (103) is in fluidconnection with flotation tank (115). A plurality of gas bubbles isreleased in the coagulation chamber and cause the metal particles tofloat towards the top of the fluid in the flotation chamber (104). Themetal particles begin to be separated in the flotation chamber (104). Anidentical system without reference numerals is shown in FIG. 6A.

Referring now to FIGS. 7B and 7D, there is shown a second embodiment ofa system for removing particles from a contaminated metalworking fluid,generally designated (200). The second embodiment is similar to thefirst embodiment of the system for removing particles from acontaminated metalworking fluid except that the pressurized fluid isinjected perpendicular to the flow of the contaminated fluid from theoutside of the flow of the contaminated fluid toward the center, therebycreating shear, rather than from the center of the flow of thecontaminated fluid.

A pressurization tank (not pictured) for pressurizing a cleanmetalworking fluid with a gas is in fluid connection via conduit (201)with a hydraulic shear device (202). The hydraulic shear device (202) isin fluid connection with a conduit (204) for contaminated metalworkingfluid. Conduit (204) is in fluid connection with coagulation channel(203). The hydraulic shear device (202) releases an aerated, pressurizedfluid substantially perpendicular to the flow of the contaminatedmetalworking fluid into coagulation channel (203). Hydraulic sheardevice (202) comprises nozzle (216) for injecting fluid perpendicular tothe direction of coagulation channel (203) and the flow of thecontaminated metalworking fluid. Two nozzles (216) are shown in FIG.11B, but any suitable number of nozzles can be used. In someembodiments, nozzles (216) are arranged approximately equidistant aroundthe circumference of the coagulation channel (203). In some embodiments,the nozzles are positioned in such a manner to alternate theirapplication of the shear forces by a finite distance positioned in thedirection of flow/shear and aimed opposite of each other. Although twospray nozzles are shown in FIGS. 7B and 7D, there can be more nozzles asdeemed suitable for this application, preferably if they are in pairsand alternate each other by a finite distance.

Still referring to FIGS. 7B and 7D, the contaminated metalworking fluidand the aerated fluid are contacted through the hydraulic shear and areflowed through the coagulation chamber (203). In some embodiments thecoagulation channel may have a length sufficient to provide a laminarflow of a fluid through the coagulation chamber for at least about 1second. Coagulation channel (203) is preferably substantially straight,as shown in FIGS. 7B and 7D. The coagulation channel (203) is in fluidconnection with flotation tank (215). A plurality of gas bubbles isreleased in the coagulation chamber and cause the metal particles tofloat towards the top of the fluid in the flotation chamber (204). Themetal particles can be removed in the flotation tank (215). An identicalsystem to FIG. 7B without reference numerals is shown in FIG. 7A. Anidentical system to FIG. 7D without reference numerals is shown in FIG.7C.

Referring now to FIG. 8B, an embodiment of a multistage particle removalsystem (450) is shown. The multistage particle removal system (450)includes a conduit (451) for contaminated fluid, such as fluid that hasbeen used in a metalworking process. Conduit (451) is in fluidconnection with gravity settling tank (452) which has a sealable opening(453) where large and/or dense particles can be removed after settlingin the gravity settling tank (452) due to gravity. Gravity settling tank(452) is in fluid connection with pump lift station (455) via conduit(454). Pump lift station (455) includes a level control (456) which isin electrical connection with pump (457). Pump lift station (455) is influid connection with pump (457) and contaminated metalworking fluid canbe flowed from the gravity settling tank (452) to the pump lift station(453) and pumped by pump (455) via conduit (404) to the laminarcoagulation zone (403) of system (400) for removing particles from acontaminated metalworking fluid. System (400) may in some embodiments bea system utilizing hydraulic shear to separate emulsion droplets frommetal particles in the contaminated metalworking fluid, such as thesystems shown in FIGS. 6 and 7 . System (400) includes a pump (417) forsending clean metalworking fluid from flotation tank (415) to an airsaturation pressure vessel (also referred to as a pressurization vessel)(418). The clean metalworking fluid is pressurized with a gas, such as(but not limited to) atmospheric air, in the air saturation pressurevessel (418). The pressurization vessel (418) is in fluid connectionwith a conduit (401) for directing the pressurized or aeratedmetalworking fluid to the coagulation zone (403). Coagulation channel(403) is preferably substantially straight, as shown in FIG. 8B. System(400) includes a pressure release valve (417) for releasing the pressurein the aerated metalworking fluid and allowing gas bubbles to form. Suchpressure release valve (417) may be arranged to provide a hydraulicshear as the aerated metalworking fluid is combined with thecontaminated metalworking fluid, for example, as shown in FIGS. 6A-6Band 7A-7D. Coagulation zone (403) is in fluid connection with flotationtank (415) where metal particles can be removed from the fluid, such asby skimming rakes (419). Clean metal working fluid can be flowed fromflotation tank (415) to the pressurization vessel (418) or via conduit(458) to be used in a metalworking process. An identical system withoutreference numerals is shown in FIG. 8A.

Referring now to FIG. 9B, there is shown a third embodiment of a systemfor removing particles from a contaminated metalworking fluid, generallydesignated (300). The third embodiment is similar to the firstembodiment of the system for removing particles from a contaminatedmetalworking fluid except instead of a hydraulic shear device, the thirdembodiment includes a mechanical shear device (316) for separatingemulsion droplets from metal particles.

A pressurization tank (301) for pressurizing a clean metalworking fluidwith a gas is in fluid connection with an inner pipe (305). Inner pipe(305) has a first end (312) and a second end (313). The second end (313)of inner pipe (305) extends into a coagulation chamber (303). A firstend cap (307) is sized to seal the first end (312) of the inner pipe(305) and second end cap (308) is sized to seal the second end (313) ofthe inner pipe (305). Rod (309) has a first end (310) which extendsthrough first end cap (307) and attaches to a pressure adjustment handle(314) and a second end (311) which attaches to second end cap (308). Rod(309) extends through the inner pipe (305) and is capable of pushing thesecond end cap (308) off of the second end (313) of the inner pipe (305)to release a first fluid (e.g., an aerated fluid) flowing through theinner pipe (305) into coagulation chamber (303). Rod (309) is alsocapable of pulling the second end cap (308) on the second end (313) ofthe inner pipe (305) to seal the flow of fluid out of the inner pipe(305) through the second end (313). The movement of rod (309) can becontrolled by the pressure adjustment handle (314).

Still referring to FIG. 9B, a contaminated metalworking fluid flowsthrough conduit (304) to mechanical shear device (316) which appliesshear to separate emulsion droplets from metal particles in themetalworking fluid. Conduit (304) is in fluid connection withcoagulation chamber (303) to allow contaminated metalworking fluid toflow through conduit (304), through mechanical shear device (316) andinto coagulation channel (303). The aerated fluid released out of thesecond end (313) of the inner pipe (305) and the contaminated fluidreleased from the conduit (304) are flowed together in a laminar flowthrough the coagulation chamber (303). In some embodiments thecoagulation channel may have a length sufficient to provide a laminarflow of a fluid through the coagulation channel for at least about 1second. As shown in FIG. 9B, coagulation channel (303) is preferablysubstantially straight. The coagulation channel (303) is in fluidconnection with flotation tank (315). A plurality of gas bubbles isreleased in the coagulation chamber and cause the metal particles tofloat towards the top of the fluid in the flotation tank (315). Themetal particles can be removed in the flotation tank (315). An identicalsystem without reference numerals is shown in FIG. 9A.

Referring now to FIG. 10B, an embodiment of a multistage particleremoval system (550) is shown. The multistage particle removal system(550) includes a conduit (551) for contaminated fluid, such as fluidthat has been used in a metalworking process. Conduit (551) is in fluidconnection with gravity settling tank (552) which has a sealable opening(553) where large and/or dense particles can be removed after settlingin the gravity settling tank (552) due to gravity. Gravity settling tank(552) is in fluid connection with pump lift station (555) via conduit(554). Pump lift station (555) includes a level control (556) which isin electrical connection with pump (557). Pump lift station (555) is influid connection with pump (557) and contaminated metalworking fluid canbe flowed from the gravity settling tank (552) to the pump lift station(553) and pumped by pump (555) via conduit (504) to the laminarcoagulation zone (503) of system (500) for removing particles from acontaminated metalworking fluid. System (500) may in some embodiments bea system utilizing mechanically generated shear to separate emulsiondroplets from metal particles in the contaminated metalworking fluid,such as the system shown in FIGS. 9A-9B. System (500) includes a pump(517) for sending clean metalworking fluid from flotation tank (515) toan air saturation pressure vessel (also referred to as a pressurizationvessel) (518). The clean metalworking fluid is pressurized with a gas,such as (but not limited to) atmospheric air, in the air saturationpressure vessel (518). The pressurization vessel (518) is in fluidconnection with a conduit (501) for directing the pressurized or aeratedmetalworking fluid to the coagulation zone (503). Coagulation channel(503) is preferably substantially straight, as shown in FIG. 10B. System(500) includes a pressure release valve (517) for releasing the pressurein the aerated metalworking fluid and allowing gas bubbles to form.Coagulation zone (503) is in fluid connection with flotation tank (515)where metal particles can be removed from the fluid, such as by skimmingrakes (519). Clean metal working fluid can be flowed from flotation tank(515) to the pressurization vessel (518) or via conduit (558) to be usedin a metalworking process. An identical system without referencenumerals is shown in FIG. 10A.

FIG. 11B shows a system similar to FIGS. 10A-10B, except that the cleanmetal working fluid is flowed only from flotation tank (615) to be usedin a metalworking process. In FIG. 11B, a multistage particle removalsystem (650) includes a conduit (651) for contaminated fluid, such asfluid that has been used in a metalworking process. Conduit (651) is influid connection with gravity settling tank (652) which has a sealableopening (653) where large and/or dense particles can be removed aftersettling in the gravity settling tank (652) due to gravity. Gravitysettling tank (652) is in fluid connection with pump lift station (655)via conduit (654). Pump lift station (655) includes a level control(656) which is in electrical connection with pump (657). Pump liftstation (655) is in fluid connection with pump (657) and contaminatedmetalworking fluid can be flowed from the gravity settling tank (652) tothe pump lift station (653) and pumped by pump (655) to an airsaturation pressure vessel (also referred to as a pressurization vessel)(618). The contaminated metalworking fluid is pressurized with a gas,such as (but not limited to) atmospheric air, in the air saturationpressure vessel (618). The pressurization vessel (618) is in fluidconnection with a conduit (604) for directing the pressurized or aeratedmetalworking fluid to the coagulation channel (603). Coagulation channel(603) is preferably substantially straight, as shown in FIG. 11B. System(600) includes a mechanical shear device (616) to induce a shear forceto separate emulsion droplets from metal particles in the contaminatedmetalworking fluid and pressure release valve (617) for releasing thepressure in the aerated metalworking fluid and allowing gas bubbles toform. The pressure valve (617) is located immediately after themechanical shear device (616) so that the emulsion droplets are stillseparated from the metal particles when the gas bubbles formed and themetal particles are free to associate with the gas bubbles in thecoagulation zone (603). Coagulation zone (603) is in fluid connectionwith flotation tank (615) where metal particles can be removed from thefluid, such as by skimming rakes (619). Clean metal working fluid can beflowed from flotation tank (615) via conduit (658) to be used in ametalworking process. An identical system without reference numerals isshown in FIG. 11A.

The following clauses describe certain embodiments.

-   -   Clause 1. A method of removing metal particles from a        contaminated metalworking fluid comprising emulsion droplets and        metal particles, the method comprising:    -   pressurizing a first clean metalworking fluid with gas to        provide an aerated metalworking fluid;    -   releasing the pressure of the aerated metalworking fluid to form        a plurality of bubbles;    -   applying a shear force to the contaminated metalworking fluid to        separate the emulsion droplets from the metal particles;    -   flowing the contaminated metalworking fluid with the aerated        metalworking fluid in a laminar flow to form a combined fluid,        wherein the flowing occurs during the formation of the plurality        of bubbles and while the emulsion droplets are separated from        the metal particles, and wherein the laminar flow lasts for a        time sufficient for the plurality of bubbles to attach to the        metal particles;    -   releasing the combined fluid into a flotation tank; and    -   removing the metal particles to form a second clean metalworking        fluid.    -   Clause 2. A method for removing metal particles from a        contaminated metalworking fluid comprising emulsion droplets and        metal particles, the method comprising:    -   pressurizing the contaminated metalworking fluid with gas in a        pressurization vessel to provide an aerated metalworking fluid;    -   flowing the aerated metalworking fluid from the bottom of the        pressurization fluid to a coagulation channel;    -   applying a shear force to the aerated metalworking fluid to        separate the emulsion droplets from the metal particles;    -   reducing the pressure of the aerated metalworking fluid to        provide a plurality of bubbles, wherein the reducing the        pressure occurs after applying the shear force and while the        emulsion droplets are separated from the metal particles;    -   flowing the aerated metalworking fluid in a laminar flow through        the coagulation channel to a floatation tank, wherein the        laminar flow lasts for a time sufficient for the plurality of        bubbles to attach to the metal particles;    -   releasing the aerated metalworking fluid into the flotation        tank; and    -   removing the metal particles to provide a clean metalworking        fluid.    -   Clause 3. The method of clause 1, wherein the contacting occurs        within about 0.5 second or less after the releasing of the        pressure of the aerated metalworking fluid.    -   Clause 4. The method of clause 1, wherein the wherein the        flowing occurs within about 0.5 second or less after applying        the shear force.    -   Clause 5. The method of clause 1, wherein the shear force is a        hydraulic shear force.    -   Clause 6. The method of clause 5, wherein application of a        hydraulic shear force comprises injecting the aerated        metalworking fluid into a flow of contaminated metal working        fluid in a direction perpendicular to the flow of contaminated        metal working fluid.    -   Clause 7. The method of clause 2, wherein the reducing the        pressure is about 0.5 second or less after applying the shear        force.    -   Clause 8. The method of clause 2, wherein the reducing the        pressure occurs within 0.5 second after applying the shear        force.    -   Clause 9. The method of clause 1 or 2, wherein the shear force        is a mechanically generated shear force.    -   Clause 10. The method of clause 1 or 2, wherein the time        sufficient for the plurality of bubbles to attach to the metal        particles is at least about 1.0 second.    -   Clause 11. The method of clause 1 or 2, wherein the metal        particles have an average particle size of about 30 micron or        less.    -   Clause 12. The method of clause 1, wherein the first clean        metalworking fluid is pressurized with gas at about 3.5 bar to        about 6.2 bar for about two minutes or longer.    -   Clause 13. The method of clause 2, wherein the clean        metalworking fluid is pressurized with gas at about 3.5 bar to        about 6.2 bar for about two minutes or longer.    -   Clause 14. The method of clause 1 or 2, wherein the aerated        metalworking fluid and the contaminated metalworking fluid are        flowed in a flow ratio in a range of 1:5 (v:v) to 1:1 (v:v).    -   Clause 15. The method of clause 1 or 2 wherein the metal        particles are non-ferrous.    -   Clause 16. The method of clause 15, wherein the metal particles        comprise one or more of copper, aluminum, nickel, lead,        titanium, tungsten and molybdenum.    -   Clause 17. The method of clause 1 or 2, wherein the gas        comprises atmospheric air.    -   Clause 18. The method of clause 1 or 2, wherein the gas is        selected from nitrogen, oxygen, and ozone.    -   Clause 19. The method of clause 1 or 2, wherein the contaminated        metalworking fluid comprises an anionic emulsifier.    -   Clause 20. The method of clause 1 or 2, wherein the contaminated        metalworking fluid comprises a nonionic emulsifier.    -   Clause 21. The method of clause 1 or 2, wherein the contaminated        metalworking fluid comprises an anionic emulsifier and a        nonionic emulsifier.    -   Clause 22. The method of clause 21, wherein the nonionic        emulsifier is present at about 0.1% wt. to 20% wt of the anionic        emulsifier.    -   Clause 23. The method of clause 1 or 2, wherein the bubbles have        a size in a range of from about 10 microns to about 50 microns.    -   Clause 24. The method of clause 1 or 2, wherein the contaminated        metalworking fluid is an oil-in-water phase emulsion.    -   Clause 25. The method of clause 24, wherein the emulsion        comprises emulsion droplets having a size in a range of about 10        microns to 1 micron.    -   Clause 26. The method of clause 1 or 2, wherein the contaminated        metalworking fluid is a water-in-oil phase emulsion.    -   Clause 27. The method of clause 1 or 2, wherein the metalworking        process is a metal forming or metal removal process.    -   Clause 28. The method of clause 1 or 2, wherein the coagulation        channel is substantially straight.    -   Clause 29. The method of clause 1, wherein the amount of        emulsifier in the second clean metalworking fluid is within        about 0.1% v/v to about 15% v/v of the amount of emulsifier in        the contaminated metalworking fluid.    -   Clause 30. The method of clause 2, wherein the amount of        emulsifier in the clean metalworking fluid is within about 0.1%        v/v to about 15% v/v of the amount of emulsifier in the        contaminated metalworking fluid.    -   Clause 31. A system for removing particles from a contaminated        metalworking fluid comprising:    -   a pressurization tank;    -   a mechanical shear device;    -   a coagulation channel having a length sufficient to provide a        laminar flow of a fluid through the coagulation chamber for at        least about 1 second; and    -   a flotation tank.    -   Clause 32. A system for removing particles from a contaminated        metalworking fluid comprising:    -   a pressurization tank;    -   a hydraulic shear device;    -   a coagulation channel having a length sufficient to provide a        laminar flow of a fluid through the coagulation chamber for at        least about 1 second; and    -   a flotation tank.    -   Clause 33. The system of clause 32, wherein the hydraulic shear        device comprises:    -   an inner pipe;    -   an outer pipe surrounding the inner pipe and approximately        coaxial with the inner pipe;    -   a first end cap and a second end cap, each sized to seal an end        of the inner pipe;    -   a rod having a first end and a second end and extending through        the inner pipe and the through the first end cap, the second end        of the rod being connected to the second end cap, wherein the        rod is capable of pushing the end cap off of the second end of        the inner pipe to release a first fluid flowing through the        inner pipe in a direction perpendicular to a flow of a second        fluid through the outer pipe, and    -   wherein the rod is capable of pulling the end cap on the second        end of the inner pipe to seal the flow of fluid out of the inner        pipe through the second end.    -   Clause 34. The system of clause 32, wherein the hydraulic shear        device comprises:    -   a pipe; and    -   a nozzle for injecting a fluid perpendicular to the direction of        the pipe.    -   Clause 35. The system of clause 31 or 32, wherein the        coagulation channel is substantially straight.

Example 1: Dissolved Air Flotation (DAF) Test

A DAF test was performed with a used sample of Quakerol 111 SW todetermine the effectiveness of DAF to improve cleanliness of the fluid.The results are shown in Table 1.

TABLE 1 Measurement Initial Post DAF Dirt count @ 8 micron, mg/L 804 200Dirt count @ 1.2 micron, mg/L 920 212 Dirt count @ 0.45 micron, mg/L1150 800 Conductivity, μS/cm 970 885 Aluminum, mg/L 163 20 Iron, mg/L23.0 7.4 Chloride, mg/L 108 61 Sodium, mg/L 27 19 Calcium, mg/L 33 15Copper, mg/L 1.6 0.5 Concentration 6.0% 6.0% pH 7.7 7.7

It will be appreciated by those skilled in the art that changes could bemade to the exemplary embodiments shown and described above withoutdeparting from the broad inventive concepts thereof. It is understood,therefore, that this invention is not limited to the exemplaryembodiments shown and described, but it is intended to covermodifications within the spirit and scope of the present invention asdefined by the claims. For example, specific features of the exemplaryembodiments may or may not be part of the claimed invention and variousfeatures of the disclosed embodiments may be combined. Unlessspecifically set forth herein, the terms “a”, “an” and “the” are notlimited to one element but instead should be read as meaning “at leastone”.

It is to be understood that at least some of the figures anddescriptions of the invention have been simplified to focus on elementsthat are relevant for a clear understanding of the invention, whileeliminating, for purposes of clarity, other elements that those ofordinary skill in the art will appreciate may also comprise a portion ofthe invention. However, because such elements are well known in the art,and because they do not necessarily facilitate a better understanding ofthe invention, a description of such elements is not provided herein.

Further, to the extent that the methods of the present invention do notrely on the particular order of steps set forth herein, the particularorder of the steps should not be construed as limitation on the claims.Any claims directed to the methods of the present invention should notbe limited to the performance of their steps in the order written, andone skilled in the art can readily appreciate that the steps may bevaried and still remain within the spirit and scope of the presentinvention.

1. A method of removing metal particles from a contaminated metalworkingfluid comprising emulsion droplets and metal particles, the methodcomprising: pressurizing a first clean metalworking fluid with gas toprovide an aerated metalworking fluid; releasing the pressure of theaerated metalworking fluid to form a plurality of bubbles; applying ashear force to the contaminated metalworking fluid causing separation ofthe emulsion droplets from the metal particles; flowing the contaminatedmetalworking fluid with the aerated metalworking fluid in a laminar flowto form a combined fluid, wherein the flowing occurs after applying theshear force and during the formation of the plurality of bubbles andduring separation of the emulsion droplets from the metal particles, andwherein the laminar flow lasts for a time sufficient for the pluralityof bubbles to attach to the metal particles; releasing the combinedfluid into a flotation tank; and removing, from the combined fluid, themetal particles that have been separated from the emulsion droplets toform a second clean metalworking fluid.
 2. (canceled)
 3. The method ofclaim 1, wherein applying the shear force occurs within 0.5 second orless after the releasing of the pressure of the aerated metalworkingfluid or the flowing occurs within 0.5 second or less after applying theshear force.
 4. (canceled)
 5. The method of claim 1, wherein the shearforce is a hydraulic shear force or a mechanically generated shearforce.
 6. The method of claim 5, wherein application of the hydraulicshear force comprises injecting the aerated metalworking fluid into aflow of contaminated metal working fluid in a direction perpendicular tothe flow of contaminated metal working fluid. 7.-9. (canceled)
 10. Themethod of claim 1, wherein the time sufficient for the plurality ofbubbles to attach to the metal particles is at least 1.0 second.
 11. Themethod of claim 1, wherein at least one of (i)-(iii) applies: (i) themetal particles have an average particle size of 30 micron or less; (ii)metal particles are non-ferrous; or (iii) the metal particles compriseone or more of copper, aluminum, nickel, lead, titanium, tungsten andmolybdenum.
 12. The method of claim 1, wherein the first cleanmetalworking fluid is pressurized with gas at 3.5 bar to 6.2 bar for twominutes or longer.
 13. (canceled)
 14. The method of claim 1, wherein theaerated metalworking fluid and the contaminated metalworking fluid areflowed in a flow ratio in a range of 1:5 (v:v) to 1:1 (v:v). 15-16.(canceled)
 17. The method of claim 1, wherein the gas comprisesatmospheric air or the gas is selected from nitrogen, oxygen, and ozone.18. (canceled)
 19. The method of claim 1, wherein the contaminatedmetalworking fluid comprises: (i) an anionic emulsifier, (ii) a nonionicemulsifier, or (iii) an anionic emulsifier and a nonionic emulsifier.20. (canceled)
 21. (canceled)
 22. The method of claim 19, wherein thenonionic emulsifier of (iii) is present at 0.1% wt. to 20% wt of theanionic emulsifier.
 23. The method of claim 1, wherein the bubbles havea size in a range of from 10 microns to 50 microns.
 24. The method ofclaim 1, wherein the contaminated metalworking fluid is: (i) anoil-in-water phase emulsion; or (ii) a water-in-oil phase emulsion. 25.The method of claim 24, wherein the oil-in-water phase emulsioncomprises emulsion droplets having a size in a range of 10 microns to 1micron. 26-27. (canceled)
 28. The method of claim 1 further comprising:flowing the aerated metalworking fluid through a coagulation channel.29. The method of claim 1, wherein an amount of emulsifier in the secondclean metalworking fluid is within 0.1% v/v to 15% v/v of an amount ofemulsifier in the contaminated metalworking fluid. 30-35. (canceled) 36.The method of claim 28, wherein the coagulation channel is straight. 37.The method of claim 28, wherein the coagulation channel has a lengthsufficient to provide a laminar flow of a fluid through the coagulationchannel for at least 1 second.